The present invention relates to binuclear platinum (II) complexes which respond to organic molecular gas (vapor) in the environment to exhibit color changes and luminescent changes.
Major patent references for compounds having a vapochromic nature where the compound responds to organic molecular gas (vapor) to exhibit color and luminescent changes include the followings.
(1) U.S. Pat. No. 4,826,774 (Nagel, 1989, Vapochromic double-complex salts)
Summary: It is made of a transit metallic double-complex salt containing arenylisonitrile ligand induced with long aliphatic hydrocarbon chains, its cation is tetrakis isonitrile platinum ion and its anion is tetracyanopalladium ion. These binuclear salts exhibit new vapochromic effects and are useful as a personal badge monitor, limit monitor, optic sensor, chemical field effect transistor and related monitor application articles.
(2) U.S. Pat. No. 5,445,785 (Lancaster et al., 1995, Volatile organic compound sensing devices)
Summary: Apparatus using a vapochromic substance having a composition of an inorganic double-complex salt of which color is changed reversibly when exposed to volatile organic compound (VOC) vapors is applied for the detection of VOC vapor, detection of VOC aqueous medium, and selective detection of VOC vapor. A fundamental VOC vapochromic sensor is incorporated in various devices such as a ground probe sensor, wrist band sensor, periodic sampling monitor, soil penetrometer, evaporation purge sensor, and various vacuum-based sensors. In particular, they are applied for reversible and recyclable detection, remote detection, continuous monitoring or rapid screening in the environmental improvement and waste disposal plants. Vapochromic sensors are used in combination with various fiber optic configurations since they give a presence indication of VOC with a presence correction of VOC qualitatively and quantitatively.
(3) U.S. Pat. No. 5,766,952 (Mann et al., 1998, Vapochromic platinum-complexes and salts)
Summary: This invention relates to the following processes: indicating the presence of an organic matter vapor including a stage to determine an absorption spectrum or luminescent spectrum of platinum-platinum double complex salt or neutral platinum complex in the absence of an organic vapor; exposing the above platinum-platinum double complex salt or neutral platinum complex to an gaseous environment; and the exposure to the above gaseous environment followed by determining color, the absorption spectrum or luminescent spectrum of the above platinum-platinum double complex salt or neutral platinum complex.
The double complexes are represented by the following general chemical formulae: [Pt(CNxe2x80x94C6H4xe2x80x94R)4][PtX4], [Pt(phen)(CNxe2x80x94C6H4xe2x80x94R)2][PtX4], [Pt(bpy)(CNxe2x80x94C6H4xe2x80x94R)2][PtX4], [Pt(CNxe2x80x94C6H4xe2x80x94CnH2n+1)4][Pt(CN)4], [Pt(phen)(CNxe2x80x94C6H4xe2x80x94R)2][Pt(CN)4], [Pt(bpy)(CNxe2x80x94C6H4xe2x80x94R2)[Pt(CN)4]; n is an integer between 1 and 100, usually n=1 to 20; phen is 1,10-phenanthroline or alkyl substituted 1,10-phenanthroline; bpy is 2,2xe2x80x2-bipyridine or alkyl substituted 2,2-bipyridine; [PtX4]2xe2x88x92 can be [Pt(NO2)4]2xe2x88x92, [Pt(Cl)4]2xe2x88x92, [PtBr4]2xe2x88x92, [Pt(NCO)4]2xe2x88x92, [Pt(NCS)4]2xe2x88x92, and [Pt(oxalate)4]2xe2x88x92; and palladium analogues of [PtX4]2xe2x88x92 are allowed in bpy and phen complexes. The neutral complexes are [Pt(CNxe2x80x94C6H4xe2x80x94R)2X2], and [Pt(CNxe2x80x94C6H4xe2x80x94R)(C(Y)xe2x95x90NHxe2x80x94C6H4xe2x80x94R)X2]; n is a positive integer between 1 and 100; Y is more preferably O-alkyl, NH-alkyl, and N(alkyl)2, with n=1 to 20, Xxe2x95x90CNxe2x88x92, but the other negatively charged groups (NO2xe2x88x92, NCOxe2x88x92, NCSxe2x88x92, Clxe2x88x92, Brxe2x88x92, Ixe2x88x92, ox, etc.) can be used. One Xxe2x88x92 group is not necessarily identical.
The objective of the invention is to provide chemicals which make not only a dark-red/light-red change of color but also a near-infrared/red change of luminescence via reversible absorption/desorption of vapor of acetonitrile or ethanol, and therefore permit the observation of on-off change of visually effective luminescence and thus can become highly sensitive sensors.
The present invention relates to a binuclear platinum (II) complex represented by the following formula:
[Pt2(L)2(bpy)2]X2 or [Pt2(L)2(bpy)2]Y
(wherein L represents a bridging ligand, as well as bpy represents 2,2xe2x80x2-bipyridine, X and Y represent a monovalent anion and bivalent anion, respectively), characterized in that both of the two bridging ligands are coordinated to one platinum ion by S and to the other platinum ion by N(syn isomer).
The invention further relates to a method for producing the binuclear platinum (II) complex described in claim 1, comprised by adding [PtCl2(bpy)2] and an equivalent amount of the bridging ligand (L) to water, heating the suspension, filtrating the impurity, subsequently adding an excess salt compound containing X or Y, for example, adding an excess NH4PF6 to the resultant solution to generate precipitate, obtaining the precipitate by filtration and recrystallizing from an organic solvent.
The binuclear platinum (II) complex of the invention is structurally characterized in the syn type where two bridging ligands are coordinated to one platinum ion by S and to the other platinum ion by N.
Such structural characteristic can specifically and reversibly absorb and desorbe vapor of organic molecules such as acetonitrile, alcohols such as ethanol, and methylene chloride, and cause the color change between dark-red and light-red and simultaneously induce near-infrared/red change of luminescence, and therefore observe on-off of visually effective luminescence. Incidentally, the binuclear platinum (II) complex of the invention exhibits no change for water and chloroform.
Therefore, the present invention also relates to an organic molecular detection sensor comprising the above binuclear platinum (II) complex, and an organic molecular vapor monitor apparatus including the detection sensor by taking advantage of such a nature of the binuclear platinum (II) complex.
Further, the present invention also relates to a method for detecting volatile organic molecules in the environment by taking advantage of the color change of the above binuclear platinum (II) complex, and a method for detecting volatile organic molecules in the environment by taking advantage of the luminescent change of the above binuclear platinum (II) complex.